A liquid crystal display device is characterized by a thin thickness, lightweight, and low power consumption, and is widely used in various fields. The liquid crystal display device has been dramatically improved in display performance with the years, and is now becoming superior to a CRT (cathode-ray tube).
A display mode of the liquid crystal display device is defined by how a liquid crystal is aligned in a liquid crystal cell. Various display modes such as a TN (Twisted Nematic) mode, an MVA (Multi-domain Vertical Alignment) mode, an IPS (In-Plain Switching) mode, and an OCB (Optically Compensated Birefringence) mode have been known as a display mode of the liquid crystal display device.
A large number of liquid crystal display devices adopting any of these display modes have been produced. Among these, a liquid crystal display device adopting the TN mode is generally and widely used, for example. However, the liquid crystal display device adopting the TN mode has disadvantages of low-speed response, narrow viewing angle, and the like.
In the MVA mode, liquid crystal molecules are aligned in a plurality of directions due to fringe fields generated by (i) slits respectively formed on pixel electrodes on an active matrix substrate and (ii) protrusions (ribs) respectively formed on counter electrodes of a counter substrate, the protrusions controlling the alignments of the liquid crystal molecules. The MVA mode achieves a wide viewing angle because the liquid crystal molecules incline to a plurality of directions (forms Multi-domain) while a voltage is applied. However, the MVA mode has a disadvantage of low-speed response like the TN mode.
Among the above-mentioned display modes, the IPS mode (see Non Patent Literature 3, for example) achieves a wide viewing angle with a simpler arrangement. The IPS mode is arranged so that liquid crystal molecules are switched in a plane, thereby achieving a remarkably wide viewing angle. However, the IPS mode also has a disadvantage of low-speed response like the TN mode and the MVA mode.
Among the above-mentioned display modes, the OCB mode (see Non Patent Literature 1 and Non Patent Literature 2, for example) is the only display mode that can achieve a high-speed response with a simple arrangement in which a nematic liquid crystal is simply sandwiched between two substrates that have been subjected to an alignment process so as to have a parallel alignment. Therefore, the OCB mode is highly expected particularly for an in-car system and the like which requires response performance at low temperatures.